The garrison was built back when Err'loq's was a thriving trade hub and sand strider destination (don't ask). It was made to stand against the local native uprising and make sure whichever republic, empire, principality, or crime family laid claim to nearby space got their cut of the action. Today it still stands, strong and unmovable, and still extorts all it can from the locals.
The Old Garrison is a sloped wall, barbell-shaped construct occupying roughly 14 x 6 inches and 3 & 3/4 inches tall. A single, entry point, 360-degree slitted windows / firing slots, and a low reinforced fighting wall on the roof. The roof is removable for full access to the structure. Made of sturdy 3mm MDF board and precision laser cut.